HER2 positive/hormone positive vs HER2 positive/hormone negative breast cancer: Clinical presentation, prognosis, and time to relapse—A retrospective cohort study.

e13017 Background: Breast cancer is among the most common malignancies globally, placing a substantial strain on healthcare systems and affecting patient populations significantly. Human epidermal growth factor receptor 2-positive (HER2-positive) breast cancer represents a significant portion of these cases. This retrospective study aims to elucidate the prognostic and therapeutic differences between HER2-positive/Hormone-positive vs HER2-positive/Hormone-negative breast cancer to help form personalized treatment strategies. Methods: This study was conducted at Liaquat National Hospital, Karachi, Pakistan, utilizing medical records of 189 patients with newly diagnosed HER2+/HR+ and HER2+/HR- invasive breast carcinoma from 2014 to 2019. Data on stage at presentation, response to neoadjuvant chemotherapy, patterns of relapse, and survival outcomes were collected. Statistical analysis using chi-squared/Fisher’s exact tests evaluated differences between subgroups, focusing on the influence of hormone receptor status on clinical and therapeutic parameters. Results: Data were analyzed using SPSS v27. Qualitative variables were presented as frequencies and percentages, and quantitative variables as mean ± SD. Independent t-tests and chi-square/Fisher's exact tests were used, with p ≤ 0.05 considered significant. The study included 189 HER2-positive patients (mean age 47.36 ± 9.81 years). Hypertension was the most common comorbidity (18%). No significant age difference was found between hormone-positive (48.13 ± 9.17) and hormone-negative (46.35 ± 10.55) patients (p = 0.218). Comorbidity was associated with hormone status (p = 0.041), but IDC grade, stage, menopausal status, family history, addiction, and tumor laterality were not (p > 0.05). Metastatic patterns showed no differences between groups (p > 0.05). In patients who relapsed after adjuvant treatment, time to relapse was comparable between hormone-positive (17.00 ± 20.67 months) and hormone-negative (22.57 ± 15.48 months, p = 0.579). Ki67 levels were significantly higher in hormone-negative patients (p = 0.004). Survival at 2 years was similar (p = 0.593); however, at 5 years, hormone-positive patients demonstrated a significant survival advantage (80% vs. 61.9%, p = 0.017). Conclusions: HER2-positive breast cancer outcomes differ by hormone receptor status. While stage, response to therapy, and relapse patterns were similar, hormone-negative patients had higher Ki67 levels, indicating more aggressive disease. Hormone-positive patients showed significantly better 5-year survival, highlighting the need for tailored treatment strategies.